RF Heating of Implants in MRI: Electromagnetic Analysis and Solutions

Cho, Youngdae; Yoo, Hyoungsuk

doi:10.13104/imri.2020.24.2.67

Cited by 8 publications

(5 citation statements)

References 83 publications

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“…Since these implantable electronics are metallic in nature, unwanted heating and hot spots must be studied to prevent injury to the patient. Significant studies have been conducted showing various techniques such as specific placement or decoy elements and show varying degrees of heating and minimization and image impact [333], [334], [335], [336], [337], [338], [339], [340], [341], [342], [343], [344]. These studies include looking at the impact of electromagnetic interactions with implanted lead wires [337], helical stents [338], catheters [339], as well as a wide range of other implantable devices [342], [343], [344].…”

Section: Microwave Enhanced Magnetic Resonance Imagingmentioning

confidence: 99%

“…Recent papers looked at the intrinsic performance of RF coils through a numerical study that should provide a metric for MRI designers to compare coil quality across manufacturers and customers [321], [323], [342]. Increased computing power also allows researchers to electromagnetically model the human body to predict unwanted effects such as heating, hot spots, or wavelength-dependent light and dark regions in the images [333], [334], [335], [336], [337], [338], [339], [340], [341], [342], [343], [344], [350].…”

Section: Microwave Enhanced Magnetic Resonance Imagingmentioning

confidence: 99%

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Applications of Microwaves in Medicine

Chiao

Lin

et al. 2023

IEEE J. Microw.

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Advances and updates in medical applications utilizing microwave techniques and technologies are reviewed in this paper. The article aims to provide an overview of enablers for microwave medical applications and their recent progress. The emphasis focuses on the applications of microwaves, in the following order, for 1) signal and data communication for implants and wearables through the human body, 2) electromagnetic energy transfer through tissues, 3) noninvasive, remote or in situ physical and biochemical sensing, and 4) therapeutic purposes by changing tissue properties with controlled thermal effects. For signal and data communication and wireless power transfer, implant and wearable applications are discussed in the categories of pacemakers, endoscopic capsules, brain interfaces, intraocular, cardiac and intracranial pressure sensors, neurostimulators, endoluminal implants, artificial retina, smart lenses, and cochlear implants. For noninvasive sensing, remote vital sign radar, biological cell probing, magnetic resonance and microwave imaging, biochemical, blood glucose, hydration and biomarker sensing applications are introduced. For therapeutic uses, the developments of microwave ablation, balloon angioplasty, and hyperthermia applications are reviewed. The scopes of this article mainly concentrate on the research and development efforts in the past 20 years. Recent review articles on specific topics are cited with accomplishment highlights and trends deliberated. At the end of this article, a brief history of the IEEE Microwave Theory and Techniques Society (MTT-S) Biological Effects and Medical Applications committee and the contributions by its members to the promotion and advancement of microwave technologies in medical fields are chronicled.

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Section: Microwave Enhanced Magnetic Resonance Imagingmentioning

confidence: 99%

Section: Microwave Enhanced Magnetic Resonance Imagingmentioning

confidence: 99%

Applications of Microwaves in Medicine

Chiao

Lin

et al. 2023

IEEE J. Microw.

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“…Radiofrequency (RF) heating during magnetic resonance imaging (MRI) is a significant safety concern for patients with deep brain stimulation (DBS). [1][2][3][4] DBS can regulate abnormal brain activities in neurologic disorders such as Parkinson's disease, dystonia, and tremor. [5][6][7] It is also considered a promising treatment for psychiatric disorders 8 such as obsessive-compulsive disorder.…”

Section: Introductionmentioning

confidence: 99%

“…Radiofrequency (RF) heating during magnetic resonance imaging (MRI) is a significant safety concern for patients with deep brain stimulation (DBS) 1–4 . DBS can regulate abnormal brain activities in neurologic disorders such as Parkinson's disease, dystonia, and tremor 5–7 .…”

Section: Introductionmentioning

confidence: 99%

A workflow for predicting radiofrequency‐induced heating around bilateral deep brain stimulation electrodes in MRI

Zulkarnain,

Sadeghi‐Tarakameh,

Thotland

et al. 2023

Medical Physics

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BackgroundHeating around deep brain stimulation (DBS) in magnetic resonance imaging (MRI) occurs when the time‐varying electromagnetic (EM) fields induce currents in the electrodes which can generate heat and potentially cause tissue damage. Predicting the heating around the electrode contacts is important to ensure the safety of patients with DBS implants undergoing an MRI scan. We previously proposed a workflow to predict heating around DBS contacts and introduced a parameter, equivalent transimpedance, that is independent of electrode trajectories, termination, and radiofrequency (RF) excitations. The workflow performance was validated in a unilateral DBS system.PurposeTo predict RF heating around the contacts of bilateral (DBS) electrodes during an MRI scan in an anthropomorphic head phantom.MethodsBilateral electrodes were fixed in a skull phantom filled with hydroxyethyl cellulose (HEC) gel. The electrode shafts were suspended extracranially, in a head and torso phantom filled with the same gel material. The current induced on the electrode shaft was experimentally measured using an MR‐based technique 3 cm above the tip. A transimpedance value determined in a previous offline calibration was used to scale the shaft current and calculate the contact voltage. The voltage was assigned as a boundary condition on the electrical contacts of the electrode in a quasi‐static (EM) simulation. The resulting specific absorption rate (SAR) distribution became the input for a transient thermal simulation and was used to predict the heating around the contacts. RF heating experiments were performed for eight different lead trajectories using circularly polarized (CP) excitation and two linear excitations for one trajectory. The measured temperatures for all experiments were compared with the simulated temperatures and the root‐mean‐squared errors (RMSE) were calculated.ResultsThe RF heating around the contacts of both bilateral electrodes was predicted with ≤ 0.29°C of RMSE for 20 heating scenarios.ConclusionThe workflow successfully predicted the heating for different bilateral DBS trajectories and excitation patterns in an anthropomorphic head phantom.

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“…The International Society for Magnetic Resonance in Medicine (ISMRM) has recently endorsed the best practice or guidance on RF safety-related MRI experiments and/or numerical assessments [ 7 , 8 ]. Several studies have assessed RF safety during MRI scans for workers [ 9 , 10 , 11 , 12 ] and patients, including adults with implanted medical devices [ 13 , 14 , 15 , 16 , 17 ] and the general public [ 18 , 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Proposed Safety Guidelines for Patient Assistants in an Open MRI Environment

Hong²,

Choi³

2022

IJERPH

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The wide-open side of an open magnetic resonance imaging (MRI) system allows a patient to easily contact the patient assistant during MRI scans. A wide-open-shaped magnet is highly effective when interventional procedures are necessary. Patient assistants can provide comfort by holding a part of the patient’s body. Because current regulations or guidelines are concerned with only patient radio frequency (RF) safety, investigations on the safety of patient assistants exposed to high-magnetic field MRI (up to 1.2 T) are required. In this study, five different poses of patient assistants were numerically simulated at a 1.2 T open MRI system to determine the impact of poses on the RF exposure level. The 10-g averaged specific absorption rate (SAR) levels were analyzed for the poses of each patient assistant wearing gloves. Compared with the patient, up to 29.8% of the patient SAR was observed in the patient assistant. When the patient assistant wore latex gloves, a 63.7% reduction in the 10-g averaged SAR level was observed, which could be a remedy to minimize possible RF hazards. To prevent possible RF hazards during MRI scans, certain clauses regarding the patient assistant’s poses or wearing gloves must be added to the existing MRI screening forms.

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RF Heating of Implants in MRI: Electromagnetic Analysis and Solutions

Cited by 8 publications

References 83 publications

Applications of Microwaves in Medicine

Applications of Microwaves in Medicine

A workflow for predicting radiofrequency‐induced heating around bilateral deep brain stimulation electrodes in MRI

Proposed Safety Guidelines for Patient Assistants in an Open MRI Environment

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